Sealants useful in aerospace and other applications are often pre-mixed frozen compositions (PMF) or two-part systems. In two-part systems, a first component contains a main polymer, such as a polysulfide polymer and/or a polythioether polymer, together with a number of additional materials. The first component does not contain a curing agent, which is instead in the second component. The two components are manufactured, packaged separately, and mixed together immediately before use.
Unlike two-component systems, which require mixing the curing paste and the base before use, PMFs may be cured by external factors, such as temperature. For this reason, PMFs must be frozen at, for example, −40° F. to −80° F. in order to suppress or slow the curing reaction. When the PMFs are later brought to room temperature, the curing rate increases significantly. PMFs offer the convenience of being ready for use without mixing and therefore can be more cost- and time-effective than certain two-part systems. However, existing PMFs have limited shelf-lives, must be stored at very low temperatures such as −40° F. to −80° F., and require mixing of the base component and activator followed by immediate freezing to slow the curing reaction. The requirement to store PMFs at low temperature prior to use can be inconvenient and/or expensive.